A very high proportion of HIV-positive patients with skin and soft tissue infection with MRSA experience a rapid recurrence of the condition, according to a report by US investigators in the October 1st edition of the Journal of Acquired Immune Deficiency Syndromes.
Skin and soft tissue infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are increasing in the US, and the community-associated USA300 strain is common in people with HIV.
Factors that increase the risk of MRSA infection are common in people with HIV including low CD4 cell count, extensive use of antibiotics, sexual risk behaviour, and injecting drug use.
Investigators wished to determine the rate of MRSA recurrence in HIV-positive patients receiving care at the San Francisco General Hospital HIV Clinic. They also wished to see if any strains of MRSA, clinical factors, behaviours or antibiotic treatments increased the risk of MRSA recurrence.
The study involved patients with culture-proven skin and soft tissue MRSA infection who received care at the clinic between 2002 and 2006. A total of 62 patients were included in the investigators’ analysis. These patients had a median age of 39 years, 80% were men and 63% were gay men. Just under half were taking antiretroviral therapy and 25% had a CD4 cell count above 500 cells/mm3. The most common sites for initial MRSA infection were the buttocks/genital region (32%) and the head and neck (31%). Most of the patients (54, 87%) had a skin or soft tissue infection with the USA300 strain of MRSA.
Forty-four (71%) patients experienced a recurrence of MRSA with a median of 136 days. In twelve of these patients (27%) the site of MRSA skin or soft tissue infection was the same as the site of the initial infection.
The investigators were able to find no factors that were significantly associated with a risk of MRSA infection recurring.
Drug-sensitivity tests were conducted on the MRSA cultured from 14 patients experiencing a recurrence of the infection. These tests showed that the strains of MRSA in all 14 patients were susceptible to treatment with trimethoprim-sulfamethoxazole and rifampicin.
This testing also showed that antibiotic treatment for the first MRSA infection could not predict the pattern of resistance seen in the MRSA recurrence.
Tests on 14 individuals showed that six patients had recurrent infection with the USA300 strain.
“The results of this study demonstrate a remarkably high rate of skin and soft tissue infection recurrence in HIV-infected primary care patients presenting for initial community-onset skin and soft tissue infections caused by MRSA”, write the investigators.
The investigators note that a previous study has shown a high rate of MRSA recurrence involving the USA300 strain in the buttock/genital area of men who have sex men. They write, “taken together, these two studies suggest that reacquisition of MRSA infection via skin-to-skin contact with individuals infected or colonized with MRSA may play an important role in the pathogenesis of recurrent MRSA disease in patients with HIV.”
They conclude, “the HIV primary care practitioner faced with a patient presenting with an initial skin or soft tissue infection with a culture positive for MRSA can reasonably expect that the patient will more likely than not have a recurrence”. They recommend that antibiotic susceptibility tests should be performed in patients experiencing such a recurrence and that “efforts to reduce transmission and/or colonization should be considered”.
Graber CJ et al. Recurrence of skin and soft tissue infection caused by methicillin-resistant staphylococcus aureus in an HIV primary care clinic. J Acquir Immune Defic Syndr 49: 231-3, 2008.